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Abstract:

An anisotropic conductive film composition for bonding a semiconductor
device, the composition including: a binder system including a urethane
resin having a glass transition temperature of about 100° C. or
higher, a radical polymerizable compound, an organic peroxide, and
conductive particles.

Claims:

1. A semiconductor device bonded by an anisotropic conductive film, the
anisotropic conductive film comprising: a binder system including a
urethane resin having a glass transition temperature of about 100.degree.
C. or higher; a radical polymerizable compound; an organic peroxide; and
conductive particles.

2. The semiconductor device as claimed in claim 1, wherein the urethane
resin has a weight average molecular weight of about 50,000 to about
200,000 g/mol.

3. The semiconductor device as claimed in claim 1, wherein the urethane
resin is a polyurethane acrylate resin.

4. The semiconductor device as claimed in claim 3, wherein the
polyurethane acrylate resin is prepared by polymerization of: an
isocyanate; an acrylate; and a polyol or a diol.

5. The semiconductor device as claimed in claim 1, wherein the urethane
resin is present in an amount of about 35 to about 80 parts by weight,
based on 100 parts by weight of the solid content of the anisotropic
conductive film.

6. The semiconductor device as claimed in claim 1, wherein the
anisotropic conductive film includes: about 50 to about 90 parts by
weight of the binder system; about 5 to about 40 parts by weight of the
radical polymerizable compound; about 0.1 to about 10 parts by weight of
the organic peroxide; and about 0.1 to about 10 parts by weight of the
conductive particles; all parts being based on 100 parts by weight of the
solid content of the anisotropic conductive film.

7. The semiconductor device as claimed in claim 1, wherein the binder
system further includes at least one of a thermoplastic resin and an
acrylic copolymer.

8. A semiconductor device, comprising: a substrate including electrodes
and a space between the electrodes, and an anisotropic conductive film on
the substrate in the space between the electrodes, the anisotropic
conductive film including a urethane resin and having: an average bubble
area of 10% or less based on an area of the space between the electrodes;
and an adhesive strength of about 800 gf/cm or more.

9. The semiconductor device as claimed in claim 8, wherein the urethane
resin has a glass transition temperature of about 100.degree. C. or
higher.

10. The semiconductor device as claimed in claim 8, wherein the urethane
resin is a polyurethane acrylate resin.

11. The semiconductor device as claimed in claim 8, wherein the urethane
resin is present in an amount of about 35 to about 80 parts by weight,
based on 100 parts by weight of the solid content of the anisotropic
conductive film.

12. The semiconductor device as claimed in claim 8, wherein the average
bubble area and the adhesive strength of the anisotropic conductive film
are measured after pressing the anisotropic conductive film into the
space between the electrodes at a temperature of at least about
60.degree. C., a pressure of at least about 1.0 MPa, and for a period of
time of at least about 1 second.

13. The semiconductor device as claimed in claim 12, wherein the average
bubble area and the adhesive strength of the anisotropic conductive film
are measured after pressing the anisotropic conductive film into the
space between the electrodes at a temperature of about 200.degree. C., a
pressure of about 3.0 MPa, and for a period of time of about 5 seconds.

14. An anisotropic conductive film for bonding a semiconductor device,
the anisotropic conductive film comprising a urethane resin and having:
an average bubble area of 10% or less when the anisotropic conductive
film is pressed in spaces between electrodes on a substrate at a
temperature of 200.degree. C., a pressure of 3.0 MPa, and for a period of
time of 5 seconds, the average bubble area being an average area of
bubbles based on an area of the spaces; and an adhesive strength of about
800 gf/cm or more when the anisotropic conductive film is pressed in
spaces between electrodes on a substrate at a temperature of 150.degree.
C., a pressure of 3.0 MPa, and for a period of time of 5 seconds.

15. The anisotropic conductive film as claimed in claim 14, wherein the
urethane resin has a glass transition temperature of about 100.degree. C.
or higher.

16. The anisotropic conductive film as claimed in claim 15, wherein the
urethane resin is a polyurethane acrylate resin.

17. The anisotropic conductive film as claimed in claim 16, wherein the
polyurethane acrylate resin is present in an amount of about 35 to about
80 parts by weight, based on 100 parts by weight of the solid content of
the anisotropic conductive film.

Description:

BACKGROUND

[0001] 1. Field

[0002] Embodiments relate to an anisotropic conductive film composition
and a semiconductor device bonded by the anisotropic conductive film
composition.

[0003] 2. Description of the Related Art

[0004] Adhesives may be used in semiconductor devices to bond different
elements, and the bonded surfaces of these elements may include irregular
features. Such adhesives should have suitable electrical properties
depending on the elements being bonded. Such adhesives should also have
suitable adhesive properties after being bonded to the elements.

SUMMARY

[0005] Embodiments are directed to an anisotropic conductive film
composition for bonding a semiconductor device, the composition
including: a binder system including a urethane resin having a glass
transition temperature of about 100° C. or higher, a radical
polymerizable compound, an organic peroxide, and conductive particles.

[0006] The urethane resin may have a weight average molecular weight of
about 50,000 to about 200,000 g/mol.

[0007] The urethane resin may be a polyurethane acrylate resin.

[0008] The polyurethane acrylate resin may be prepared by polymerization
of: an isocyanate, an acrylate, and a polyol or a diol.

[0009] The urethane resin may be present in an amount of about 35 to about
80 parts by weight, based on 100 parts by weight of the solid content of
the anisotropic conductive film composition.

[0010] The anisotropic conductive film composition may include: about 50
to about 90 parts by weight of the binder system, about 5 to about 40
parts by weight of the radical polymerizable compound, about 0.1 to about
10 parts by weight of the organic peroxide, and about 0.1 to about 10
parts by weight of the conductive particles, all parts being based on 100
parts by weight of the solid content of the anisotropic conductive film
composition.

[0011] The binder system may further include at least one of a
thermoplastic resin and an acrylic copolymer.

[0012] Embodiments are also directed to a semiconductor device, including:
a substrate including electrodes and a space between the electrodes, and
an anisotropic conductive film on the substrate in the space between the
electrodes, the anisotropic conductive film including a urethane resin
and having: an average bubble area of 10% or less based on an area of the
space between the electrodes, and an adhesive strength of about 800 gf/cm
or more.

[0013] The urethane resin may have a glass transition temperature of about
100° C. or higher.

[0014] The urethane resin may be a polyurethane acrylate resin.

[0015] The urethane resin may be present in an amount of about 35 to about
80 parts by weight, based on 100 parts by weight of the solid content of
the anisotropic conductive film.

[0016] The average bubble area and the adhesive strength of the
anisotropic conductive film may be measured after pressing the
anisotropic conductive film into the space between the electrodes at a
temperature of at least about 60° C., a pressure of at least about
1.0 MPa, and for a period of time of at least about 1 second.

[0017] The average bubble area and the adhesive strength of the
anisotropic conductive film may be measured after pressing the
anisotropic conductive film into the space between the electrodes at a
temperature of about 200° C., a pressure of about 3.0 MPa, and for
a period of time of about 5 seconds.

[0018] Embodiments are also directed to an anisotropic conductive film for
bonding a semiconductor device, the anisotropic conductive film including
a urethane resin and having: an average bubble area of 10% or less when
the anisotropic conductive film is pressed in spaces between electrodes
on a substrate at a temperature of 200° C., a pressure of 3.0 MPa,
and for a period of time of 5 seconds, the average bubble area being an
average area of bubbles based on an area of the spaces, and an adhesive
strength of about 800 gf/cm or more when the anisotropic conductive film
is pressed in spaces between electrodes on a substrate at a temperature
of 150° C., a pressure of 3.0 MPa, and for a period of time of 5
seconds.

[0019] The urethane resin may have a glass transition temperature of about
100° C. or higher.

[0020] The urethane resin may be a polyurethane acrylate resin.

[0021] The polyurethane acrylate resin may be present in an amount of
about 35 to about 80 parts by weight, based on 100 parts by weight of the
solid content of the anisotropic conductive film.

DETAILED DESCRIPTION

[0022] Korean Patent Application No. 10-2011-0118240 filed on Nov. 14,
2011, in the Korean Intellectual Property Office, and entitled:
"Anisotropic Conductive Film and Semiconductor Device," is incorporated
by reference herein in its entirety.

[0023] Exemplary embodiments of the present invention will now be
described in detail. Details apparent to those skilled in the art may be
omitted herein. As used herein, the indefinite article "a", "an", and
derivations thereof do not exclude a plurality. It will also be
understood that when a layer or element is referred to as being "on"
another layer or substrate, it can be directly on the other layer or
substrate, or intervening layers may also be present. Further, it will be
understood that when a layer is referred to as being "under" another
layer, it can be directly under, and one or more intervening layers may
also be present. In addition, it will also be understood that when a
layer is referred to as being "between" two layers, it can be the only
layer between the two layers, or one or more intervening layers may also
be present.

[0024] As used herein, the term "and/or" includes any and all combinations
of one or more of the associated listed items. Expressions such as "at
least one of," when preceding a list of elements, modify the entire list
of elements and do not modify the individual elements of the list.

[0025] Unless specified otherwise, the processing order of a process
should not be limited by the order in which the process is described. For
example, two processes that are described successively may be performed
substantially simultaneously, and may be performed in an opposite order
to the description.

[0026] According to an embodiment, a semiconductor device may be bonded by
an anisotropic conductive film composition which may include:

[0027] a binder system including a urethane resin having a glass
transition temperature (Tg) of about 100° C. or higher;

[0028] a radical polymerizable compound;

[0029] an organic peroxide; and

[0030] conductive particles.

[0031] The urethane resin may be, e.g., a polyurethane acrylate. The
polyurethane acrylate may be prepared by polymerization of an isocyanate,
an acrylate, and a compound having more than one hydroxyl group (e.g., a
polyol and/or a diol).

[0032] The isocyanate may include at least one aromatic, aliphatic, or
alicyclic diisocyanate. Examples of such isocyanates may include
tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate,
cyclohexylene-1,4-diisocyanate, methylene bis(4-cyclohexyl isocyanate),
isophorone diisocyanate, and 4,4-methylene bis(cyclohexyl diisocyanate).
Preferably, aromatic isocyanates may be used.

[0033] The acrylate that is polymerized in order to prepare the
polyurethane acrylate may include, e.g., hydroxyl acrylates and amine
acrylates.

[0034] The polyol may include a compound having at least two hydroxyl
groups in a molecular chain thereof, e.g., a polyester polyol, a
polyether polyol and a polycarbonate polyol. Examples of the polyether
polyol may include polyethylene glycol, polypropylene glycol, and
polytetraethylene glycol. The polyol may be obtained through condensation
of a dicarboxylic acid compound and a diol compound.

[0036] Examples of the diol compound may include ethylene glycol,
propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol,
dipropylene glycol, triethylene glycol, tetraethylene glycol, dibutylene
glycol, 2-methyl-1,3-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, and
1,4-cyclohexanedimethanol. Diols may be condensed with a dicarboxylic
acid compound to produce the above-described polyols, and/or diols may be
used as the compound having more than one hydroxyl group in the
preparation of the polyurethane acrylate without being condensed with a
dicarboxylic acid compound.

[0037] The polymerization to produce the polyurethane acrylate may be
carried out by a suitable method. For example, methyl ethyl ketone may be
used as a solvent at 50% by volume (vol %), the amount of a polyol may be
60% by weight, the amount of isocyanate and acrylate may be 40% by
weight, a molar ratio of acrylate to isocyanate may be 1.0, and the
reaction may be conducted at 90° C. and 1 atm for 5 hours using a
suitable catalyst, e.g., dibutyltin dilaurylate. The polyol and/or diol
may be reacted with the isocyanate to form a prepolymer before being
reacted with the acrylate.

[0038] The urethane resin may have a weight average molecular weight of
about 50,000 to about 200,000 g/mol. If the weight average molecular
weight of the urethane resin is within this range, the film may exhibit
sufficient hardness, the urethane may be easier to synthesize, and the
adhesion of the film may be improved.

[0039] The urethane resin may be present in an amount of about 35 to about
80 parts by weight based on 100 parts by weight of the solid content of
the anisotropic conductive film composition, preferably about 40 to about
80 parts by weight. If the amount of the urethane resin is within this
range, the film may exhibit sufficient adhesion, and flowability may be
improved, which may make it easier to maintain stable connection. The
binder system may further include at least one of a thermoplastic resin
and an acrylic copolymer.

[0041] The thermoplastic resin may have a weight average molecular weight
of about 1,000 to about 1,000,000 g/mol. Within this range, film strength
may be improved, phase separation may be reduced, and deterioration of
adhesion may be reduced (e.g., by increasing tack to an adherend).

[0042] The thermoplastic resin may be present in an amount of 0 to about
40 parts by weight based on 100 parts by weight of the solid content of
the anisotropic conductive film composition, preferably about 5 to about
30 parts by weight. If the amount of the thermoplastic resin is within
this range, the dispersion of conductive particles may be improved and
deterioration of flowability may be reduced, which may make it easier to
maintain stable connection.

[0044] The acrylic copolymer may be present in an amount of 0 to about 40
parts by weight based on 100 parts by weight of the solid content of the
anisotropic conductive film composition, preferably about 5 to about 30
parts by weight. If the amount of the acrylic copolymer is within this
range, the film may be substantially prevented from having soft
properties (which may cause the film to exhibit poor reworkability after
preliminary pressing in a pressing process), and the film may have
improved strength and tack, which may reduce separation in preliminary
pressing. The radical polymerizable compound may be a suitable radical
polymerizable compound. For example, the radical polymerizable compound
may include at least one of acrylates, methacrylates, and maleimide
compounds, which may be used as monomers, oligomers, or a combination of
monomers and oligomers.

[0047] The radical polymerizable compound may be present in an amount of
about 5 to about 40 parts by weight based on 100 parts by weight of the
solid content of the anisotropic conductive film composition. If the
amount of the radical polymerizable compound is within this range,
reliability and overall flowability may improve (i.e., curing density
after final pressing may increase). As a result, insufficient contact
between conductive particles and a circuit substrate may be prevented at
the time of bonding, and connection resistance may decrease, thereby
increasing connection reliability. If the amount of the radical
polymerizable compound is within this range, it may also be easier to
foult the anisotropic conductive film, and adhesive properties may be
improved. The organic peroxide used in the present invention may be a
polymerization initiator, which may serve as a curing agent that
generates free radicals upon heating or exposure to light.

[0049] The organic peroxide may be present in an amount of about 0.1 to
about 10 parts by weight based on 100 parts by weight of the solid
content of anisotropic conductive film composition. If the amount of the
organic peroxide is within this range, deterioration in physical
properties after final pressing (which may be caused by a retarded curing
reaction), may be prevented. Also, if the amount of the organic peroxide
is within this range, brittleness of the anisotropic conductive film
after curing may decrease, which may make it easier to achieve complete
removal of the anisotropic conductive film during reworking.

[0051] The particle size of the conductive particles may be within a range
of, e.g., about 2 to about 30 μm, and the particle size may be
selected depending on the pitch of circuits to be used.

[0052] The conductive particles may be present in an amount of about 0.1
to about 10 parts by weight based on 100 parts by weight of the solid
content of the anisotropic conductive film composition. If the amount of
the conductive particles is within this range, defective connection may
be reduced (defective connection may be caused by a decrease in area for
connection when terminals are misaligned during connection), and
insulation failure may be reduced.

[0053] In an embodiment, a semiconductor device may include a substrate
that includes electrodes and a space between the electrodes, and the
anisotropic conductive film may be in the space between the electrodes.
The anisotropic conductive film may include a urethane resin, and may
have an average bubble area of 10% or less in the space between the
electrodes, and an adhesive strength of 800 gf/cm or more.

[0054] The spaces between the electrodes of the semiconductor device may
be, e.g., gaps between the electrodes in a printed circuit board (PCB),
which may be filled with an anisotropic conductive film composition
during pressing.

[0055] The area of the spaces between the electrodes may be a suitable
area. For example, the area of the space may be as follows: there may be
3 or 4 chip on films (COFs) in a single PCB, and each COF may be provided
with about 100 electrodes. The area of spaces between electrodes may be
about 250 pitches in width and about 3 mm in length. The area of bubbles
generated in the spaces between the about 100 electrodes may be
calculated on average, thereby obtaining the average bubble area of the
anisotropic conductive film.

[0056] The anisotropic conductive film according to the present invention
may have an average bubble area of 10% or less based on the area in the
space between the electrodes. The average bubble are may be calculated
after pressing the anisotropic conductive film at, e.g., 200° C.
and 3.0 mMPa for 5 seconds. If the bubble area is within this range,
adhesive strength of the film may increase, and process defects and
deterioration in bonding reliability may be reduced.

[0057] Adhesive strength may be measured at 50 mm/min by a 90° peel
strength tester (H5KT, Tinius Olsen). The adhesive strength may be
measured after pressing the anisotropic conductive film in the space
between the electrodes, e.g., at 150° C. and 3.0 MPa for 5
seconds.

[0058] The anisotropic conductive film may have an adhesive strength of
800 gf/cm or more. If the anisotropic conductive film has an adhesive
strength within this range, adhesion between terminals of a circuit
employing the film may be strengthened, and defective connection and
bonding may be reduced.

[0059] According to an embodiment, a semiconductor device may include: a
wiring substrate, an anisotropic conductive film on a first side of the
wiring substrate (which may be the side on which a chip is meant to be
mounted), and a semiconductor chip on the anisotropic conductive film,
where the anisotropic conductive film may include urethane resin having a
glass transition temperature of about 100° C. or higher. The
anisotropic conductive film may be between the semiconductor chip and the
first side of the wiring substrate, and the anisotropic conductive film
may be directly bonded to the semiconductor chip and/or the first side of
the wiring substrate.

[0060] The wiring substrate and the semiconductor chip may be a suitable
wiring substrate and semiconductor chip. For example, the wiring
substrate may be a PCB and the semiconductor chip may be a COF.

[0061] A method of manufacturing a semiconductor device may be a suitable
method.

[0062] The glass transition temperature (Tg) may be measured by a suitable
method. For example, the glass transition temperature may be measured as
follows: the resin to be measured may be converted to a solid state by
evaporation of a solvent, and the Tg may be measured by using a thermal
mechanical analyzer (TMA, TA Instruments) while elevating temperature
from, e.g., -40 to 200° C. at 10° C./min.

[0063] The anisotropic conductive film may be obtained by a suitable
method. For example, the anisotropic conductive film may be obtained by
dissolving and/or liquefying a binder resin in an organic solvent, adding
other components thereto, and stirring the solution for a suitable period
of time to obtain the anisotropic conductive film composition. The
anisotropic conductive film composition may then be applied to a release
film at a thickness of about 10 to about 50 μm, and the solution may
be dried to volatilize the organic solvent.

[0064] The following Examples and Comparative Examples are provided in
order to set forth particular details of one or more embodiments.
However, it will be understood that the embodiments are not limited to
the particular details described. Further, the Comparative Examples are
set forth to highlight certain characteristics of certain embodiments,
and are not to be construed as either limiting the scope of the invention
as exemplified in the Examples or as necessarily being outside the scope
of the invention in every respect.

EXAMPLE 1

Preparation of Anisotropic Conductive Film Including a Urethane Resin
Having a Tg of About 100° C. or Higher

[0065] (1) Preparation of Anisotropic Conductive Film Composition

[0066] An anisotropic conductive film composition was prepared using the
following materials:

[0067] as a binder system, 40 parts by weight of polyurethane acrylate
having a weight average molecular weight of 100,000 g/mol and a Tg of
110° C.; 20 parts by weight of an acrylonitrile butadiene
copolymer (1072CGX, Zeon Chemical) dissolved at 25 vol % in
toluene/methyl ethyl ketone; and 20 parts by weight of an acrylic
copolymer having a weight average molecular weight of 100,000 g/mol
(AOF7003, Aekyung Chemical) dissolved at 45 vol % in toluene/methyl ethyl
ketone, was used. The polyurethane acrylate was synthesized from 60 wt %
of polyol, 39 wt % of aromatic isocyanate, and 1 wt % of hydroxy
(meth)acrylate using 50 vol % methyl ethyl ketone as a solvent. First,
the polyol and the aromatic isocyanate were reacted to synthesize a
prepolymer having an aromatic isocyanate terminal. Then, the prepolymer
having the aromatic isocyanate terminal and the hydroxy (meth)acrylate
were reacted to prepare the polyurethane acrylate resin. The molar ratio
of hydroxy (meth)acrylate to prepolymer having an aromatic isocyanate
iinal was 1.0, and polymerization of the polyurethane acrylate resin was
carried out at 90° C. and 1 atm for 5 hours using dibutyltin
dilaurate as a catalyst.

[0068] as a radical polymerizable compound, 15 parts by weight of an
acrylate monomer (4-HBA, OSAKA) was used;

[0069] as an organic peroxide, 2 parts by weight of benzoyl peroxide
(Hansol Chemical) was used; and

[0070] as conductive particles, 3 parts by weight of conductive Ni
particles having a particle size of 5 μm were used;

[0071] based on 100 parts by weight of the solid content of the
anisotropic conductive film.

[0072] (2) Preparation of Anisotropic Conductive Film

[0073] The combination prepared above was stirred at a rate such that the
conductive particles were not pulverized, and at room temperature
(25° C.) for 60 minutes. The combination was formed using a
casting knife into a 35 μm thick anisotropic conductive film on a
polyethylene base film that had been subjected to silicone release
surface treatment. The anisotropic conductive film was dried at
60° C. for 5 minutes.

EXAMPLE 2

Preparation of Anisotropic Conductive Film Including Urethane Resin Having
a Tg of About 100° C. or Higher

[0074] An anisotropic conductive film was prepared according to the same
procedure as in Example 1, except that 50 parts by weight of a
polyurethane acrylate having a weight average molecular weight of 100,000
g/mol and a Tg of 110° C.; 15 parts by weight of an acrylonitrile
butadiene copolymer (1072CGX, Zeon Chemical) dissolved at 25 vol % in
toluene/methyl ethyl ketone; and 15 parts by weight of an acrylic
copolymer having a weight average molecular weight of 100,000 g/mol
(AOF7003, Aekyong Chemical) dissolved at 45 vol % in toluene/methyl ethyl
ketone were used based on 100 parts by weight of the solid content of the
anisotropic conductive film.

COMPARATIVE EXAMPLE 1

Preparation of Anisotropic Conductive Film Including Urethane Resin Having
a Tg of less than 100° C.

[0075] An anisotropic conductive film was prepared according to the same
procedure as in Example 1, except that as a binder system, 40 parts by
weight of a polyurethane acrylate having a weight average molecular
weight of 30,000 g/mol and a Tg of 10° C.; 20 parts by weight of
an acrylonitrile butadiene copolymer (1072CGX, Zeon Chemical) dissolved
at 25 vol % in toluene/methyl ethyl ketone; and 20 parts by weight of an
acrylic copolymer having a weight average molecular weight of 100,000
g/mol (AOF7003, Aekyong Chemical) dissolved at 45 vol % in toluene/methyl
ethyl ketone were used based on 100 parts by weight of the solid content
of the anisotropic conductive film. The polyurethane acrylate was
synthesized from 60 wt % of polyol, 39 wt % of aliphatic isocyanate and 1
wt % of hydroxy(meth)acrylate using 50 vol % methyl ethyl ketone as a
solvent. First, the polyol and the aliphatic isocyanate were reacted to
synthesize a prepolymer having an aliphatic isocyanate terminal. Then,
the prepolymer having the aliphatic isocyanate terminal and the hydroxy
(meth)acrylate were reacted to prepare the polyurethane acrylate resin.
The molar ratio of hydroxy (meth)acrylate to prepolymer having an
aliphatic isocyanate terminal was 1.0, and polymerization of the
polyurethane acrylate resin was carried out at a temperature of
90° C. and a pressure of 1 atm for 5 hours using dibutyltin
dilaurate as a catalyst.

COMPARATIVE EXAMPLE 2

Preparation of Anisotropic Conductive Film Including Styrene Resin

[0076] An anisotropic conductive film was prepared according to the same
procedure as in Example 1, except that as a binder system, 40 parts by
weight of an acrylonitrile-a-methylstyrene resin having a weight average
molecular weight of 120,000 g/mol (AP-TJ, Cheil Industries) dissolved at
40 vol % in toluene/methyl ethyl ketone; 20 parts by weight of an
acrylonitrile butadiene copolymer (1072CGX, Zeon Chemical) dissolved at
25 vol % in toluene/methyl ethyl ketone; and 20 parts by weight of an
acrylic copolymer having a weight average molecular weight of 100,000
g/mol (AOF7003, Aekyong Chemical) dissolved at 45 vol % in toluene/methyl
ethyl ketone were used based on 100 parts by weight of the solid content
of the anisotropic conductive film.

[0077] The parts by weight of the components in the compositions in
Examples 1 and 2, and Comparative Examples 1 and 2 are listed in Table 1.

[0078] In order to measure the area of bubbles generated after final
pressing, each of the anisotropic conductive films according to Examples
1 and 2, and Comparative Examples 1 and 2 was attached to a PCB (pitch:
200 μm, terminal: 100 μm, distance between terminals: 100 μm
terminal height: 35 μm) and to a COF (pitch: 200 μm, terminal: 100
μm, distance between terminals: 100 μm, terminal height: 8 μm)
under the following conditions:

[0079] 1) Preliminary pressing: 60° C., 1 second, 1.0 MPa

[0080] 2) Final pressing: 200° C., 5 seconds, 3.0 MPa

[0081] After five specimens of each of the anisotropic conductive films
according to Examples 1 and 2, and Comparative Examples 1 and 2 were
attached as above, the specimens were evaluated as to the area of bubbles
generated in spaces between the electrodes, as explained below.

[0082] The portions of the anisotropic conductive films in 10 of the
spaces between the electrodes were photographed using an Olympus BX51,
and the area in which bubbles were generated in each of these portions
was measured based on the area of each of the 10 spaces between the
electrodes (250 pitches in width, 3 mm in length).

EXPERIMENTAL EXAMPLE 2

Measurement of Adhesive Strength

[0083] In order to measure the adhesive strength after final pressing,
each of the anisotropic conductive films according to Examples 1 and 2,
and Comparative Examples 1 and 2 was attached to a PCB (pitch: 200 μm,
terminal: 100 μm, distance between terminals: 100 μm, terminal
height: 35 μm) and to a COF (pitch: 200 μm, terminal: 100 μm,
distance between terminals: 100 μm, terminal height: 8 μm) under
the following conditions:

[0084] 1) Preliminary pressing: 60° C., 1 second, 1.0 MPa

[0085] 2) Final pressing: 150° C., 5 seconds, 3.0 MPa

[0086] After five specimens of each of the anisotropic conductive films
according to Examples 1 and 2, and Comparative Examples 1 and 2 were
attached as above, the specimens were prepared and evaluated as to
adhesive strength at 50 mm/min using a 90° peel strength tester
(H5KT, Tinius Olsen).

[0087] Results of Experimental Examples 1 and 2, and Comparative Examples
1 and 2 are illustrated in Table 2.

[0088] The anisotropic conductive films including urethane resin having a
Tg of about 100° C. or higher according to Examples 1 and 2 had a
reduced area of bubbles generated after final pressing, which was about 4
or 5% of the area of the spaces between electrodes, and also exhibited an
improved adhesive strength of about 900 to about 1,000 gf/cm or more.
Thus, both suppression of bubble generation and adhesive strength may be
improved when a urethane resin having a Tg of about 100° C. or
higher is used.

[0089] On the other hand, the anisotropic conductive film including a
urethane resin having a Tg of less than 100° C. according to
Comparative Example 1 had an improved adhesive strength but had an
increased area of bubbles after final pressing of 40%. Also, the
anisotropic conductive film including styrene instead of urethane
according to Comparative Example 2 had a reduced area of bubbles after
final pressing, but exhibited a reduced adhesive strength of 520 gf/cm.
Neither of Comparative Examples 1 and 2 were able to achieve both the
improved suppression of bubble generation and improved adhesive strength
of Examples 1 and 2.

[0090] By way of summary and review, anisotropic conductive films may
refer to film-like adhesives in which conductive particles (e.g., metal
particles or metal-coated polymer particles) are dispersed in a resin
(e.g., an epoxy resin). Anisotropic conductive films may include a
polymer layer having electric anisotropy and an adhesive property, and
may exhibit conductive properties in the thickness direction of the films
and insulating properties in the surface direction thereof. If an
anisotropic conductive film is disposed between connection substrates
(e.g., circuit boards) and is subjected to heating and pressing under
particular conditions, terminals of the connection substrates may be
electrically connected through conductive particles, and an insulating
adhesive resin may fill in spaces between adjacent terminals to isolate
the conductive particles from each other, thereby high insulation
performance between the terminals may be provided.

[0091] If panels become larger and wirings are enlarged, spaces between
electrodes may become wider. Because a connection substrate may expand
due to pressing under heat and pressure in bonding, and may contract back
after bonding, an adhesive composition may expand and contract to a
substantial degree, which may cause bubbles to be generated and may cause
a deterioration in filling effect of the adhesive composition.

[0092] Thus, it may be advantageous for an adhesive composition to be
capable of withstanding expansion and contraction of a connection
substrate due to heat and pressure. It may be particularly advantageous
for an adhesive composition to have fewer bubbles generated in pressing,
e.g., due to hardness of the adhesive composition. However, if a hard
binder resin is used, the anisotropic conductive films may undergo
reduction of adhesion causing process failure. That is, it may be
difficult to achieve both suppression of bubble generation and excellent
adhesion at the same time. However, as demonstrated above, the
anisotropic conductive film of the embodiments may be able to generate
fewer bubbles after pressing and exhibit excellent adhesion.

[0093] Exemplary embodiments have been disclosed herein, and although
specific terms are employed, they are used and are to be interpreted in a
generic and descriptive sense only and not for purpose of limitation.
Accordingly, it will be understood by those of ordinary skill in the art
that various changes in form and details may be made without departing
from the spirit and scope of the present invention as set forth in the
following claims.